<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- 内嵌式 -->
    <style>
       h2{
         background-color: blue;
       }
    </style>
    <!-- 外链式 -->
    <link rel="stylesheet" href="one.css">

    <!-- 导入--了解 -->
    <style>
        @import "two.css";
        /* @import url("two.css"); */
    </style>
</head>
<body>
    <h4>4444</h4>
    <h4>4444</h4>

    <h3>3333</h3>
    <h3>3333</h3>

    <h2>2222</h2>
    <h2>2222</h2>
    <!-- 行内样式法 -->
    <h1 style="background-color: red;">1111</h1>
    <h1 style="background-color: red;">1111</h1>
</body>
</html>